Are the three (3) security updates for .NET Framework 4.6/4.6.1 being offered via Windows Update or are you attempting to install them manually for some reason?
Is it a 656 error or a 0x80070643(0x656) error?
Are you in the habit of using "registry cleaners" (e.g., CCleaner's Registry Cleaner component; Comodo System Cleaner; Advanced SystemCare; Advanced System Optimizer; Glary Utilities; McAfee QuickClean; AVG Quick Tune; AVG PC TuneUp; Norton Registry Cleaner; Norton PC Tuneup; PCTools Optimiser; PC Doctor; Registry Mechanic; RegCure; RegClean Pro; Registry Booster; SpeedUpMyPC; System Mechanic; TuneUp Utilities; WinMaximizer; WinSweeper; Wise Care 365; Wise Cleaner)?